1. Field of Invention
The present invention pertains to the field of recording heads. More particularly, this invention relates to a robust recording head suitable for near contact operations with recording media.
2. Art Background
Recording media such as magnetic tape and disk are commonly used in a wide variety of information storage applications. Such a recording media is usually constructed of a magnetically alterable material that is capable of emanating a magnetic field or flux that varies along its surface according to the content of the information stored on the recording media. Such a recording media is typically subdivided into storage areas or transitions. Typically, the storage density of a recording media increases as the surface dimensions of the storage areas on the recording media decreases.
Information is usually read from such recording media with a recording head that is positioned near the recording media as the recording media moves with respect to the recording head. A recording head typically includes a sensing element that senses the magnetic flux emanating from the recording media. Typically, the resistivity of the sensing element changes in response to the magnetic flux emanating from the recording media. A sensing element that changes resistivity in response to a magnetic field is usually referred to as a magneto-resistive sensing element.
Prior magneto-resistive sensing elements typically include one or more ferromagnetic elements whose resistivity changes in response to magnetic flux. Prior magneto-resistive sensing elements include anisotropic sensing elements in which a sense current flows along planes of the ferromagnetic elements. Prior magneto-resistive sensing elements also include spin tunneling sensing elements in which a sense current flows perpendicular to the planes of the ferromagnetic elements through a dielectric barrier.
The sensing element in prior recording heads, whether anisotropic or spin tunneling, is usually positioned near the interface between the recording head and the recording media where the intensity of the magnetic flux being sensed is greatest. Typically, a recording head and its sensing element must be positioned in near contact with the recording media in order to sense weak magnetic fields and in order to differentiate among different storage areas of a high density recording media.
Collisions can occur between the recording head and the recording media during such near contact operations, particulary with removable recording media. Such collisions can result in deformation of the sensing element which is typically located near the interface to the recording media. Unfortunately, such deformation can change the finely tuned magnetic properties of the sensing element and reduce the sensitivity of the sensing element to the magnetic flux emanating from the recording media. Such wear to the sensing element can reach a point where the recording head can no longer reliably read the recording media. Collisions between the recording media and the sensing element can also introduce thermal spikes into the sensing element. Unfortunately, such thermal spikes usually cause a variation in the resistivity of the sensing element, thereby introducing noise into the read operation.
In addition, prior recording heads having a sensing element positioned near the interface to the recording media are subject to a variety of other ill effects. For example, such a sensing element is often subject to damage from corrosion that occurs near the interface to the recording media. Moreover, recording heads having a sensing element near the recording media typically include conductors which are placed near the interface to the recording media. This can result in corrosion and smearing effects and can result in short circuits between the conductors and the shields of the recording head.
Furthermore, resistivity changes in a typical prior sensing element usually gives rise to a voltage potential on the sensing element. Such a potential on the sensing element may result in an electrical short circuit between the sensing element and the shield of a prior recording head. The potential difference between the sensing element the shield can also cause a potential difference between the sensing element and the recording media which can cause read noise in the sensing element.